The invention relates to the field of energy storage, in particular to storing energy in the precisely controlled mechanical deformation of single or highly ordered assemblies of nanotube molecules, and to recovering it at a later time in order to perform useful work, for example to power an electronic device or a motor vehicle.
The deformation of elastic springs, made for example out of rubber or steel, is one of the oldest and best-known forms of energy storage. It has been widely used to power clocks and wrist watches as well as, albeit much less widely, a means of powering electronic devices such as radios (Trevor Baylis, UK patent #2,262,324 A) or vehicles such as bicycles (Jason Dunkley, U.S. Pat. No. 6,557,877 B2). The advantages of mechanical springs over other forms of small-scale, portable energy storage include high reliability, durability, and efficiency. Their disadvantage lies in their relatively low energy storage density, which is about 600 Joule per liter for steel springs. This value has improved only modestly over the last century, despite the progress that has been made in materials science.
The discovery and development of methods for synthesizing nanotube molecules has greatly changed the prospects for improving the energy storage density of mechanical springs, at least at the microscopic scale. It is well-known, for example, that in the continuum limit the mechanical properties single carbon nanotubes would make extremely good springs. It has however been quite difficult to demonstrate these properties experimentally, although suggestive studies have been performed on the compression of highly disordered macroscopic assemblies of carbon nanotubes (“Mechanical Energy Storage in Carbon Nanotube Springs,” S. A. Chesnokov, V. A. Nalimova, A. G. Rinzler, R. E. Smalley and J. E. Fischer, Physical Review Letters 82, 343-346, 1999) as well as on the imprecisely controlled tension of single nanotubes (“Strength and Breaking Mechanism of Multiwalled Carbon Nanotubes under Tensile Load,” Min-Feng Yu, O. Lourie, M. J. Dyer, K. Moloni, T. F. Kelly and R. S. Ruoff, Science Magazine 287, 637-640, 2000). It has further been suggested that films of aligned carbon nanotubes could be useful in absorbing shocks (see for example “Super-Compressible Foamlike Carbon Nanotube Films,” A. Cao, P. L. Dickrell, W. G. Sawyer, M. N. Ghasemi-Nejhad and P. M. Ajayan, Science Magazine 310, 1307-1310, 2005). Finally, it has recently been shown that synthesis of nanotubes within Micro-Electro-Mechanical Systems (MEMS) facilitates the precise positioning of single or formation of microscale assemblies of multiple nanotubes (see e.g. Anastasios John Hart, “Chemical, Mechanical and Thermal Control of Substrate-Bound Carbon Nanotube Growth,” Massachusetts Institute of Technology Ph.D. dissertation, 2006).
What has not been accomplished or even attempted is to use the mechanical deformation of single or assemblies of multiple nanotube molecules, either carbon, boron nitride or any other elemental composition, as a means of storing energy for subsequent practical uses. In order to do this, it is necessary to either manipulate large numbers of isolated, noninteracting, single nanotube molecules with submicron precision, or to apply large forces to dense, highly ordered assemblies of many interacting nanotube molecules which may be millimeters in overall size. The object of this invention is to utilize the mechanical deformation of nanotube molecules or highly ordered assemblies of such as a means of storing energy and subsequently using that energy for such practical purposes as powering machinery or electronic devices.